Vue and JavaScript's bad practices

Well I like very much how Vue works and want to learn it deeper.
But the main question that bothers me is about JavaScript and its bad practices.

When I began to learn Vanilla JS,
I loved idea of onClick="do_something" that to make an event listener separately.
And this idea worked awesome with my code I was tinkering about while learning,
but when I posted that portion of code on other forum for opinion,
I got bombarded by "Bad Practices of JavaScript" adepts,
that is to keep code separate and so on and on.